Acoustic detection of radiotracked foraging bats in temperate lowland forests

During the recent years studies of bat activity are predominantly based on ultrasound detection. However this method suffers from several biases such as different species call ranges, temporal and habitat-related variability. In order to test the bias linked to the detection of whispering gleaning bats in temperate lowland forests, we equipped several individuals of Myotis bechsteinii and Plecotus auritus with transmitters and followed them on their foraging grounds where we simultaneously recorded echolocation calls. Our results highlight the very low detectability of these species whose presence was ascertained at the recording station. On the other hand, we detected the presence of many other species. We suggest methodological recommendations for ultrasound detection whenever gleaning bat species are concerned.